rxrpc: Fix trace-after-put looking at the put connection record

rxrpc_put_*conn() calls trace_rxrpc_conn() after they have done the
decrement of the refcount - which looks at the debug_id in the connection
record.  But unless the refcount was reduced to zero, we no longer have the
right to look in the record and, indeed, it may be deleted by some other
thread.

Fix this by getting the debug_id out before decrementing the refcount and
then passing that into the tracepoint.

Fixes: 363deeab6d0f ("rxrpc: Add connection tracepoint and client conn state tracepoint")
Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 45556fe..38a97e8 100644 (file)
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -546,10 +546,10 @@ TRACE_EVENT(rxrpc_peer,
            );
 
 TRACE_EVENT(rxrpc_conn,
-           TP_PROTO(struct rxrpc_connection *conn, enum rxrpc_conn_trace op,
+           TP_PROTO(unsigned int conn_debug_id, enum rxrpc_conn_trace op,
                     int usage, const void *where),
 
-           TP_ARGS(conn, op, usage, where),
+           TP_ARGS(conn_debug_id, op, usage, where),
 
            TP_STRUCT__entry(
                    __field(unsigned int,       conn            )
@@ -559,7 +559,7 @@ TRACE_EVENT(rxrpc_conn,
                             ),
 
            TP_fast_assign(
-                   __entry->conn = conn->debug_id;
+                   __entry->conn = conn_debug_id;
                    __entry->op = op;
                    __entry->usage = usage;
                    __entry->where = where;

diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c
index 00c095d..c1b1b7d 100644 (file)
--- a/net/rxrpc/call_accept.c
+++ b/net/rxrpc/call_accept.c
@@ -84,7 +84,7 @@ static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
                smp_store_release(&b->conn_backlog_head,
                                  (head + 1) & (size - 1));
 
-               trace_rxrpc_conn(conn, rxrpc_conn_new_service,
+               trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_service,
                                 atomic_read(&conn->usage), here);
        }
 

diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index 3f1da1b..700eb77 100644 (file)
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -212,7 +212,8 @@ rxrpc_alloc_client_connection(struct rxrpc_conn_parameters *cp, gfp_t gfp)
        rxrpc_get_local(conn->params.local);
        key_get(conn->params.key);
 
-       trace_rxrpc_conn(conn, rxrpc_conn_new_client, atomic_read(&conn->usage),
+       trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_client,
+                        atomic_read(&conn->usage),
                         __builtin_return_address(0));
        trace_rxrpc_client(conn, -1, rxrpc_client_alloc);
        _leave(" = %p", conn);
@@ -985,11 +986,12 @@ rxrpc_put_one_client_conn(struct rxrpc_connection *conn)
 void rxrpc_put_client_conn(struct rxrpc_connection *conn)
 {
        const void *here = __builtin_return_address(0);
+       unsigned int debug_id = conn->debug_id;
        int n;
 
        do {
                n = atomic_dec_return(&conn->usage);
-               trace_rxrpc_conn(conn, rxrpc_conn_put_client, n, here);
+               trace_rxrpc_conn(debug_id, rxrpc_conn_put_client, n, here);
                if (n > 0)
                        return;
                ASSERTCMP(n, >=, 0);

diff --git a/net/rxrpc/conn_object.c b/net/rxrpc/conn_object.c
index ed05b69..38d718e 100644 (file)
--- a/net/rxrpc/conn_object.c
+++ b/net/rxrpc/conn_object.c
@@ -269,7 +269,7 @@ bool rxrpc_queue_conn(struct rxrpc_connection *conn)
        if (n == 0)
                return false;
        if (rxrpc_queue_work(&conn->processor))
-               trace_rxrpc_conn(conn, rxrpc_conn_queued, n + 1, here);
+               trace_rxrpc_conn(conn->debug_id, rxrpc_conn_queued, n + 1, here);
        else
                rxrpc_put_connection(conn);
        return true;
@@ -284,7 +284,7 @@ void rxrpc_see_connection(struct rxrpc_connection *conn)
        if (conn) {
                int n = atomic_read(&conn->usage);
 
-               trace_rxrpc_conn(conn, rxrpc_conn_seen, n, here);
+               trace_rxrpc_conn(conn->debug_id, rxrpc_conn_seen, n, here);
        }
 }
 
@@ -296,7 +296,7 @@ void rxrpc_get_connection(struct rxrpc_connection *conn)
        const void *here = __builtin_return_address(0);
        int n = atomic_inc_return(&conn->usage);
 
-       trace_rxrpc_conn(conn, rxrpc_conn_got, n, here);
+       trace_rxrpc_conn(conn->debug_id, rxrpc_conn_got, n, here);
 }
 
 /*
@@ -310,7 +310,7 @@ rxrpc_get_connection_maybe(struct rxrpc_connection *conn)
        if (conn) {
                int n = atomic_fetch_add_unless(&conn->usage, 1, 0);
                if (n > 0)
-                       trace_rxrpc_conn(conn, rxrpc_conn_got, n + 1, here);
+                       trace_rxrpc_conn(conn->debug_id, rxrpc_conn_got, n + 1, here);
                else
                        conn = NULL;
        }
@@ -333,10 +333,11 @@ static void rxrpc_set_service_reap_timer(struct rxrpc_net *rxnet,
 void rxrpc_put_service_conn(struct rxrpc_connection *conn)
 {
        const void *here = __builtin_return_address(0);
+       unsigned int debug_id = conn->debug_id;
        int n;
 
        n = atomic_dec_return(&conn->usage);
-       trace_rxrpc_conn(conn, rxrpc_conn_put_service, n, here);
+       trace_rxrpc_conn(debug_id, rxrpc_conn_put_service, n, here);
        ASSERTCMP(n, >=, 0);
        if (n == 1)
                rxrpc_set_service_reap_timer(conn->params.local->rxnet,
@@ -420,7 +421,7 @@ void rxrpc_service_connection_reaper(struct work_struct *work)
                 */
                if (atomic_cmpxchg(&conn->usage, 1, 0) != 1)
                        continue;
-               trace_rxrpc_conn(conn, rxrpc_conn_reap_service, 0, NULL);
+               trace_rxrpc_conn(conn->debug_id, rxrpc_conn_reap_service, 0, NULL);
 
                if (rxrpc_conn_is_client(conn))
                        BUG();

diff --git a/net/rxrpc/conn_service.c b/net/rxrpc/conn_service.c
index b30e13f..123d6ce 100644 (file)
--- a/net/rxrpc/conn_service.c
+++ b/net/rxrpc/conn_service.c
@@ -134,7 +134,7 @@ struct rxrpc_connection *rxrpc_prealloc_service_connection(struct rxrpc_net *rxn
                list_add_tail(&conn->proc_link, &rxnet->conn_proc_list);
                write_unlock(&rxnet->conn_lock);
 
-               trace_rxrpc_conn(conn, rxrpc_conn_new_service,
+               trace_rxrpc_conn(conn->debug_id, rxrpc_conn_new_service,
                                 atomic_read(&conn->usage),
                                 __builtin_return_address(0));
        }